This invention relates to shadowless lighting equipment for medical use particularly capable of automatically focusing or concentrating the light on a desired portion of a patient on an operating table.
Generally, it is required that lighting equipment for medical use irradiate a person on an operating table or bed during the operation with a light without projecting shadows thereon and to easily adjust the lighting or irradiating conditions. Particularly, it has been desired to provide lighting equipment which can freely adjust the light concentration position in accordance with the intentions of a person who carries out an operation, called an operator hereinafter, during the operation.
One example of the lighting equipment of the type described above is disclosed in Japanese Patent Publication No. 25,681/1970, and this prior art of lighting equipment will be explained hereunder with reference to FIG. 1. Referring to FIG. 1, a lighting device 1' including a plurality of lamps is located on the upper portion so as to irradiate a person 2 to be operated on, called a patient hereinafter, with a light from the upper portion, and an illuminating device 3' is located between the lighting device 1' and the patient 2 to adjust the focusing or concentration position of the lighting device 1'. In an actual operation, the operator moves the illuminating device 3' to a desired portion to project frequency-modulated waves towards the lighting device 1' as shown by dot and dashed lines in FIG. 1. The light waves emitted from the illuminating device 3' are received by a light receiving unit 4' contained in the lighting device 1' so as to thereby be controlled so that an irradiation light, shown by a solid line, from the lighting device 1' can be concentrated on the predetermined position of the illuminating device 3'.
According to the manner described above, the operator can obtain a desired irradiation light only by designating the light concentration position through the illuminating device 3'.
However, in an actual operation using the lighting equipment of the prior type described above, it is difficult to accurately concentrate the light on a desired position of the patient on the operating table, this being a severe problem in the medical field.
It is also necessary to maintain an antiseptic condition in an operating room during the operation to prevent a secondary infection of a pathogenic bacteria in the patient and it is particularly necessary to maintain cleanliness of the portion of the patient to be operated on. The direct contact of foreign matter to the portion to be operated on should also be absolutely avoided. The concentration of the light from the lighting equipment on the portion to be operated on is of course required in almost all cases during the operation, and for example, in a case where it is necessary to designate the portion 5 of the patient 2 to be operated on, hatched in FIG. 1, as the light concentrating position, it is necessary to directly contact the illuminating device 3' to the portion 5 to be operated on when using the prior type lighting equipment, this being not desired from the point of view of causing a secondary infection through the illuminating device 3'.
Accordingly, in the actual operation of the prior art type of equipment, it is very difficult to concentrate the light accurately on the desired portion of the patient 2 on the operating table without causing the problems described above.